NetworkU3020

Serious

Severity: Serious - have it checked soon

Control Module Wake-up Circuit B High

6 brands affected · Generic SAE J2012 description.

Key terms: Control module: a small computer that runs one part of the car · SAE J2012: the standard generic code list

1What it means in plain English

Control modules in the car cannot communicate with each other over the vehicle network.

2Common causes

Wiring or connector fault on the communication bus
Faulty control module
Low battery voltage or poor ground
Water ingress in a connector or module
Aftermarket device interfering with the bus

3Can I drive?

Serious · drive with care

The car may run normally or may not run at all. If the module that has lost communication controls steering, brakes, park brake, charging or engine cooling, drive only if those systems feel normal; stop safely if the steering becomes heavy, a brake warning appears, or the engine temperature climbs. If the car will not start or runs badly, have it towed.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 6

Brand	Code	Description	System
Ashok Leyland CV	U3020	Control Module Wake-up Circuit B High SAE	Network
EOBD	U3020	Juhtmoduli ärkamisahel 'B' kõrge Brand	Network
Holden	U3020	Control Module Wake-up Circuit B High SAE	Network
Mitsubishi	U3020	Control Module Wake-up Circuit B High SAE	Network
Proton	U3020	Control Module Wake-up Circuit B High SAE	Network
Toyota	U3020	Control module wake-up circuit 'B' high Brand	Network

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 1

These 7-character codes are manufacturer-specific variants of U3020 and may be reported by some scan tools.

Brand	Code	Description	System
Mercedes-Benz	U302083	The security module of the control unit has detected a communication error - Value of Signal Protection Calculation Incorrect Brand	Network

6Related codes

Browse Uxxx codes or U302xx codes.